Abstract
Microencapsulation of biphenyl was carried out by varying the colloid concentration to investigate the microencapsulation of large oil droplets by the complex coacervation method. In dilute colloid solutions, the traditional model of the complex coacervation method is supported where coacervate droplets formed in the bulk solution adhere to oil droplets. However, in a solution of 3.0 wt% colloid, it was clarified that the microcapsule membrane was formed not by adhesion of the full-grown coacervate droplets, but by growth of small coacervate droplets adhering to oil droplets.
Spherical gelatine/acacia microcapsules with thicker membrane were successfully prepared by repeating the conventional complex coacervation method. The affinity of coacervate droplets to a core material is found to be a dominant factor in microencapsulation in the complex coacervation method.
The multi-layered microcapsules endured the release of encapsulated biphenyl, however the single-layered microcapsules were ruptured within a short time in release experiments, and a serious initial burst was induced. The multi-layered microcapsules prepared by repeating the conventional complex coacervation can be applied as a dosage form in the controlled release of active agents.
